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IJOG : Indonesian Journal on Geoscience

IJOG
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Published by Geological Agency of Indonesia

ISSN : 23559314 EISSN : 23559306 DOI : -

Core Subject : Science,

Earth & Planetary Sciences

The spirit to improve the journal to be more credible is increasing, and in 2012 it invited earth scientists in East and Southeast Asia as well as some western countries to join the journal for the editor positions in the Indonesia Journal of Geology. This is also to realize our present goal to internationalize the journal, The Indonesian Journal on Geoscience, which is open for papers of geology, geophysics, geochemistry, geodetics, geography, and soil science. This new born journal is expected to be published three times a year. As an international publication, of course it must all be written in an international language, in this case English. This adds difficulties to the effort to obtain good papers in English to publish although the credit points that an author will get are much higher.

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Articles 10 Documents

Search results for , issue "Vol 6, No 3 (2011)" : 10 Documents clear

Sea Surface Temperature Reconstruction Period 1993 - 2007 Based on Content Analysis of Coral Sr/Ca from the Region Labuan Bajo, Simeulue Island Cahyarini, Sri Yudawati
Indonesian Journal on Geoscience Vol 6, No 3 (2011)
Publisher : Geological Agency

DOI:Â 10.17014/ijog.v6i3.121Sea surface temperature (SST) is one of the important parameters for (paleo) climate studies. The long time series of SST data are required to understand more the climate change. Coral geochemical proxy such as Sr/Ca overcomes this problem. Coral can provide long time series of climate data continuously from present till hundreds years ago, even fossil (dead) coral can do it till thousand years ago. In this study, Sr/Ca content of Porites coral within 10 m deep from Labuan Bajo, Simeulue Island was analyzed to reconstruct SST. Coral Sr/Ca shows a strong correlation with local SST in seasonal scale as well as in the annual mean scale. Reconstructed SST data show that the monsoon between 1993 2007 strongly influence the SST variation in the Simeulue region. It supposed that the seasonal variation signal strongly influence local SST than the annual mean signal such as El Nino.

Mechanism of High Frequency Shallow Earthquake Source in Mount Soputan, North Sulawesi Suparman, Yasa; Kriswati, E.; Pamitro, Y. E.
Indonesian Journal on Geoscience Vol 6, No 3 (2011)
Publisher : Geological Agency

DOI:Â 10.17014/ijog.v6i3.122Moment tensor analysis had been conducted to understand the source mechanism of earthquakes in Soputan Volcano during October - November 2010 period. The record shows shallow earthquakes with frequency about 5 - 9 Hz. Polarity distribution of P-wave first onset indicates that the recorded earthquakes are predominated by earthquakes where almost at all stations have the same direction of P-wave first motions, and earthquakes with upward first motions.In this article, the source mechanism is described as the second derivative of moment tensor, approached with first motion amplitude inversion of P-wave at some seismic stations. The result of moment tensor decomposition are predominated by earthquakes with big percentage in ISO and CLVD component. Focal mechanism shows that the recorded earthquakes have the same strike in northeast-southwest direction with dip about 400 - 600. The sources of the high frequency shallow earthquakes are in the form of tensile-shear cracks or a combination between crack and tensile faulting.

Simulation of Groundwater Flow, Denpasar-Tabanan Groundwater Basin, Bali Province Tirtomihardjo, Heryadi; Setiawan, T.
Indonesian Journal on Geoscience Vol 6, No 3 (2011)
Publisher : Geological Agency

DOI:Â 10.17014/ijog.v6i3.123Due to the complex structure of the aquifer systems and its hydrogeological units related with the space in which groundwater occurs, groundwater flows were calculated in three-dimensional method (3D Calculation). The geometrical descritization and iteration procedures were based on an integrated finite difference method. In this paper, all figures and graphs represent the results of the calibrated model. Hence, the model results were simulated by using the actual input data which were calibrated during theÂ simulation runs. Groundwater flow simulation of the model area of the Denpasar-Tabanan Groundwater Basin (Denpasar-Tabanan GB) comprises steady state run, transient runs using groundwater abstraction in the period of 1989 (Qabs-1989) and period of 2009 (Qabs-2009), and prognosis run as well. Simulation results show, in general, the differences of calculated groundwater heads and observed groundwater heads at steady and transient states (Qabs-1989 and Qabs-2009) are relatively small. So, the groundwater heads situation simulated by the prognosis run (scenario Qabs-2012) are considerably valid and can properly beÂ used for controlling the plan of groundwater utilization in Denpasar-Tabanan GB.

Baseflow Separation of the Bribin River Upstream in Gilap Cave Flowage, Sewu Mountain Karst, Gunung Kidul, Yogyakarta Adji, T. N.
Indonesian Journal on Geoscience Vol 6, No 3 (2011)
Publisher : Geological Agency

DOI:Â 10.17014/ijog.v6i3.124Baseflow of karst underground river is a dependable flow to recharge the underground flow within dry seasons. This research was conducted in Gilap Cave, located in the upper course of Bribin River. This location has a premeditated point for sustainable karst water along the Bribin River. The main objective of this study was to separate the components of Gilap underground river flow, with the intention on defining the proportion of baseflow component during the period of measurements. A water level data logger wasÂ installed during the period between 1 May 2006 and 31 March 2007 to determine the variation of water level during the dry season, rainy season, and when the prevalence of flood events. Subsequently, several times of discharge measurements at the time of high, medium, and low water level were carried out to defineÂ stage-discharge rating curve. Then, baseflow separation was conducted using automated baseflow separation by a digital filtering method. A digital filter value was obtained from a constant recession analysis of flood events all over the year, correlated with Maximum Baseflow Indices Value (BFImax) within karst aquifers.Â The result shows that during one year, 41 flood events occured in the Gilap Cave with digital filtering value of 0.996. In addition, the calculation of baseflow percentage performs that the overall value of the ratio is close to a number of around 80%. Meanwhile, the percentages within flood events vary between the range of 45-75%. From these figures, it generally confirms that flow from small fracture is still dominant to recharge dependable flow within the upper stream of Bribin River, especially in the dry season.

Engineering Geological Characteristics of the Residual Soil, Lower Quaternary Sediments in Kertajati Region, Majalengka, West Java Sudarsono, Untung; Hasibuan, G.
Indonesian Journal on Geoscience Vol 6, No 3 (2011)
Publisher : Geological Agency

DOI:Â 10.17014/ijog.v6i3.125Only few engineering geological researches on residual soil have been conducted in Indonesia, whereas many infrastructure projects take place on undulating area and mountainous area which are composed of residual soils. The paper discusses residual soil characteristics of the Lower Quaternary sediment (Qos) inÂ Kertajati area, Majalengka. The methodology of the research consists of engineering geological mapping, in situ test using 2.5 ton penetrometer, sampling and laboratory test for index properties, Atterberg limits, grain size analysis, and strength tests. Field test analysis data show that the thickness of residual soil resting on the basement rock in the study area varies from 2.40 - 14.20 m. Upwards, it comprises sands, silts, and clays, respectively. Laboratory analysis data indicate that the residual soil is dominated by fine-grained fraction, composed of high plastic clay (CH). Relationship among engineering geological parameters was analysed using linear regression and tested using statistic method t-test to find real correlation among variables within 95 - 90% significance level.. Based on the test, there are real positive correlation with 19 degree of freedom and 5% and 10% level of significance are found in between plasticity indexes (IP) and liquid limits (LL), between plasticity indexes (IP) and clay contents (C), between specific gravities (G ) and clay contents (C). The real negative correlation with nine degree of freedom and 5% and 10% level of significance occurs in between cohesion (c) dengan friction angle (Ï). Corelation between degree of saturation (G ) and clayÂ contents (C) with 19 degree of freedom is found in 10% level of significance.

Sea Surface Temperature Reconstruction Period 1993 - 2007 Based on Content Analysis of Coral Sr/Ca from the Region Labuan Bajo, Simeulue Island Sri Yudawati Cahyarini
Indonesian Journal on Geoscience Vol 6, No 3 (2011)
Publisher : Geological Agency

DOI: 10.17014/ijog.v6i3.121Sea surface temperature (SST) is one of the important parameters for (paleo) climate studies. The long time series of SST data are required to understand more the climate change. Coral geochemical proxy such as Sr/Ca overcomes this problem. Coral can provide long time series of climate data continuously from present till hundreds years ago, even fossil (dead) coral can do it till thousand years ago. In this study, Sr/Ca content of Porites coral within 10 m deep from Labuan Bajo, Simeulue Island was analyzed to reconstruct SST. Coral Sr/Ca shows a strong correlation with local SST in seasonal scale as well as in the annual mean scale. Reconstructed SST data show that the monsoon between 1993 2007 strongly influence the SST variation in the Simeulue region. It supposed that the seasonal variation signal strongly influence local SST than the annual mean signal such as El Nino.

Mechanism of High Frequency Shallow Earthquake Source in Mount Soputan, North Sulawesi Yasa Suparman; E. Kriswati; Y. E. Pamitro
Indonesian Journal on Geoscience Vol 6, No 3 (2011)
Publisher : Geological Agency

DOI: 10.17014/ijog.v6i3.122Moment tensor analysis had been conducted to understand the source mechanism of earthquakes in Soputan Volcano during October - November 2010 period. The record shows shallow earthquakes with frequency about 5 - 9 Hz. Polarity distribution of P-wave first onset indicates that the recorded earthquakes are predominated by earthquakes where almost at all stations have the same direction of P-wave first motions, and earthquakes with upward first motions.In this article, the source mechanism is described as the second derivative of moment tensor, approached with first motion amplitude inversion of P-wave at some seismic stations. The result of moment tensor decomposition are predominated by earthquakes with big percentage in ISO and CLVD component. Focal mechanism shows that the recorded earthquakes have the same strike in northeast-southwest direction with dip about 400 - 600. The sources of the high frequency shallow earthquakes are in the form of tensile-shear cracks or a combination between crack and tensile faulting.

Simulation of Groundwater Flow, Denpasar-Tabanan Groundwater Basin, Bali Province Heryadi Tirtomihardjo; T. Setiawan
Indonesian Journal on Geoscience Vol 6, No 3 (2011)
Publisher : Geological Agency

DOI: 10.17014/ijog.v6i3.123Due to the complex structure of the aquifer systems and its hydrogeological units related with the space in which groundwater occurs, groundwater flows were calculated in three-dimensional method (3D Calculation). The geometrical descritization and iteration procedures were based on an integrated finite difference method. In this paper, all figures and graphs represent the results of the calibrated model. Hence, the model results were simulated by using the actual input data which were calibrated during the simulation runs. Groundwater flow simulation of the model area of the Denpasar-Tabanan Groundwater Basin (Denpasar-Tabanan GB) comprises steady state run, transient runs using groundwater abstraction in the period of 1989 (Qabs-1989) and period of 2009 (Qabs-2009), and prognosis run as well. Simulation results show, in general, the differences of calculated groundwater heads and observed groundwater heads at steady and transient states (Qabs-1989 and Qabs-2009) are relatively small. So, the groundwater heads situation simulated by the prognosis run (scenario Qabs-2012) are considerably valid and can properly be used for controlling the plan of groundwater utilization in Denpasar-Tabanan GB.

Baseflow Separation of the Bribin River Upstream in Gilap Cave Flowage, Sewu Mountain Karst, Gunung Kidul, Yogyakarta T. N. Adji
Indonesian Journal on Geoscience Vol 6, No 3 (2011)
Publisher : Geological Agency

DOI: 10.17014/ijog.v6i3.124Baseflow of karst underground river is a dependable flow to recharge the underground flow within dry seasons. This research was conducted in Gilap Cave, located in the upper course of Bribin River. This location has a premeditated point for sustainable karst water along the Bribin River. The main objective of this study was to separate the components of Gilap underground river flow, with the intention on defining the proportion of baseflow component during the period of measurements. A water level data logger was installed during the period between 1 May 2006 and 31 March 2007 to determine the variation of water level during the dry season, rainy season, and when the prevalence of flood events. Subsequently, several times of discharge measurements at the time of high, medium, and low water level were carried out to define stage-discharge rating curve. Then, baseflow separation was conducted using automated baseflow separation by a digital filtering method. A digital filter value was obtained from a constant recession analysis of flood events all over the year, correlated with Maximum Baseflow Indices Value (BFImax) within karst aquifers. The result shows that during one year, 41 flood events occured in the Gilap Cave with digital filtering value of 0.996. In addition, the calculation of baseflow percentage performs that the overall value of the ratio is close to a number of around 80%. Meanwhile, the percentages within flood events vary between the range of 45-75%. From these figures, it generally confirms that flow from small fracture is still dominant to recharge dependable flow within the upper stream of Bribin River, especially in the dry season.

Engineering Geological Characteristics of the Residual Soil, Lower Quaternary Sediments in Kertajati Region, Majalengka, West Java Untung Sudarsono; G. Hasibuan
Indonesian Journal on Geoscience Vol 6, No 3 (2011)
Publisher : Geological Agency

DOI: 10.17014/ijog.v6i3.125Only few engineering geological researches on residual soil have been conducted in Indonesia, whereas many infrastructure projects take place on undulating area and mountainous area which are composed of residual soils. The paper discusses residual soil characteristics of the Lower Quaternary sediment (Qos) in Kertajati area, Majalengka. The methodology of the research consists of engineering geological mapping, in situ test using 2.5 ton penetrometer, sampling and laboratory test for index properties, Atterberg limits, grain size analysis, and strength tests. Field test analysis data show that the thickness of residual soil resting on the basement rock in the study area varies from 2.40 - 14.20 m. Upwards, it comprises sands, silts, and clays, respectively. Laboratory analysis data indicate that the residual soil is dominated by fine-grained fraction, composed of high plastic clay (CH). Relationship among engineering geological parameters was analysed using linear regression and tested using statistic method t-test to find real correlation among variables within 95 - 90% significance level.. Based on the test, there are real positive correlation with 19 degree of freedom and 5% and 10% level of significance are found in between plasticity indexes (IP) and liquid limits (LL), between plasticity indexes (IP) and clay contents (C), between specific gravities (G ) and clay contents (C). The real negative correlation with nine degree of freedom and 5% and 10% level of significance occurs in between cohesion (c) dengan friction angle (φ). Corelation between degree of saturation (G ) and clay contents (C) with 19 degree of freedom is found in 10% level of significance.

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Location
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Jawa barat

INDONESIA

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Home Page

OAI Link

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Contact Name Ivan Ferdian

Contact Email ivan.ijgbg@gmail.com

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Location Kota bandung, Jawa barat INDONESIA

Abstract

Abstract

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Abstract

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Abstract

Abstract

Abstract

Contact Name
Ivan Ferdian

Contact Email
ivan.ijgbg@gmail.com

Phone
-

Journal Mail Official
ivan.ijgbg@gmail.com

Editorial Address
-

Location
Kota bandung,

Jawa barat

INDONESIA